Liquid vs. Bar in Dr. Bronner’s Pure Castile Soap

The liquid came first – peppermint to be exact. Bar soap meandered in a few decades later. While there are hardliners in both camps, the difference between liquid and bar is mostly a matter of personal preference. However, there are some differences between the two.

Here are the ingredients side by side for the unscented Baby Mild castile soap. I chose our simplest soap, which lacks any essential oils, so that the differences are easier to see.

Comparison of Liquid vs. Bar Castile Soaps

Differences explained:

  • Liquid contains more water.
    • Why: There is just enough water in the liquid soaps to keep them liquid. Any less water and the soap begins to solidify. To test this, leave the cap off your bottle for a day, and you’ll notice the soap’s starting to gel. You can reliquify it with a bit of water. (The thickness, or thinness, of the soap is not due to high water content, but to the consistency of the various oils.)
    • Effect on Performance: None
  • Liquid uses potassium hydroxide to saponify oils; bar uses sodium hydroxide.
    • Why: Hardness – sodium hydroxide produces a harder soap than potassium hydroxide. The purpose of these strong alkalis is to blast apart the oil molecules, separating the glycerin from the fatty acids. The fatty acids then reattach to the sodium or potassium ion, leaving the glycerin and water (hydroxide) free-floating. (Just a sidenote – soap cannot be made any other way. None of these alkalis are left in the soap. Check out the link at the bottom about soapmaking.)
    • Effect on Performance: None
  • Bar contains palm oil, in addition to coconut oil.
    • Why: Palm oil hardens more than coconut oil. Coconut oil, even in its solid state, is mushy, and it melts at 76° F.
    • Effect on Performance: Bar soap is slightly more moisturizing. Palm oil contains stearic acid, which some people find to be less drying than the lauric acid found in coconut oils.
  • Bar contains salt (NaCl – sodium chloride or table salt).
    • Why: Also serves as a hardener.
    • Effect on Performance: Bar soap is slightly more moisturizing. Since our bodies are slightly salty, salt water is gentler on our skin than pure water. Salty soap is, too.

Other Differences in Formulation:

  • How the Hemp and Jojoba oils are added:
    • In the liquid soaps, the hemp and jojoba oils are saponified, i.e. turned into soap, along with the coconut and olive oils. However, in the bar soaps, these two oils are added unaltered after the saponification process. This is called “superfatting” the soaps. A while back my brothers tried superfatting the liquids with the hemp and jojoba oils, but found that the oils separated out and floated to the top.
    • Effect on Performance: Bar soaps produce a creamier lather and are slightly more moisturizing.
  • Amount of Essential oils:
    • This is only relevant to the scented soaps (everything except the unscented Baby Mild). The liquid soaps have a higher percentage of the essential oils than do the bar soaps. Once again, the issue at stake is hardness. The bar soaps would soften with that high a concentration of the essential oils.
    • Effect on Performance: This is entirely a matter of personal preference. Those who like an intense whiff of scent, and those who are looking for the specific benefits of the particular essential oils, should opt for the liquids. Those who like a little scent, but not too much, the bar soap would be better.

Differences in usage:
For all body applications, they are entirely interchangeable – from washing face, hair, or body, or shaving. For around the house purposes, you would need to take the extra step of dissolving the bar soaps in water before using them in a spray bottle solution, but they are equally effective. Also, the bar soap can be grated to achieve a kind of powdered soap for laundry, although the liquid works just as well.

Volume of actual soap:
I don’t know how to de-math this, but people who put together their own recipes for cleaners might want to know this. Bar soaps are 5% water; liquids are 61%. The chemistry is a little different for both, but considering that a bar of soap weighs 5 oz, and thus 4.75 oz of it is soap, you would need 12.18 ounces (a little over 1 ½ c.) of liquid soap to equal the soap content of a 5 oz bar. Doing the math the other way, 1 cup of liquid soap equals approximately 2/3 of a bar (or 3.64 oz.) of Dr. B’s bar soap.

Bottom Line:
The Dr. Bronner’s Bar and Liquid Pure Castile soaps are interchangeable. However, the bars are slightly more moisturizing. The liquids are slightly more scented.

If you want more info on the process of soapmaking, check out this article:

If you have any other questions about what is in the soap and why or where it is sourced and why or anything else, let me know!

193 thoughts on “Liquid vs. Bar in Dr. Bronner’s Pure Castile Soap

  1. Hi Lisa, I’ve heard that castile soap can clog HE washers’ feeder hose. Would Dr. Bronner’s castile soap damage HE washers? Thanks!

    • Hi JZ – I am relying on word of mouth here since I don’t have an HE machine. Other customers have said that they have used it with no problem as long as vinegar is included in the rinse cycle. Because of my local hard water, I opt for Sal Suds in the laundry, and this doesn’t have the hard water issue that the castile soap does. Use 1-2 Tbsp.

  2. Listed above it shows that the liquid baby unscented soap does not have palm kernel oil, but when you search the product on your website, palm kernel oil IS listed as one of the ingredients. I am wondering which is true? Thanks again!

    • Hi Lauren – Thanks for pointing that out! I’m the one who is out of date. I wrote this four years ago and we just started adding palm kernel oil to our soaps this year. If palm oil or palm kernel oil gives you pause, check out how we’re sourcing it ethically and sustainably through our Fair Trade sister company Serendipalm in Ghana. Good stuff is happening here:

  3. Hi lisa!
    I have a bar of your soap here and I’m trying to figure out how to make it liquid. To use as a body wash for my babies. I boiled water but the chips didn’t melt all the way. Also wondering, is vegetable glycerin really nessacary? Or if I continue to boil water to melt them down until they are, is that fine too?? I don’t really know what I’m doing just trying to get a body wash made that I can add lavender and frankincense too. Thank you!

    • Hi Chiane – Funny you should mention this because I was just trying to do this myself. Like you, I discovered that it’s really hard to liquify our bar soap! I had to add over 6 times the amount of water as that of the soap and I still had to boil it a long time and let it sit overnight. Even then, when it cooled, it didn’t really stay liquid. it gelled up a lot. It probably could have used some more diluting. So, all this to say, liquifying the soap is not a terribly easy thing to do, but it is still possible. If it does end up being too much work for you, check out our liquid Pure Castile soaps.

  4. I’ve heard that glycerine can be drying/irritating. I have very sensitive skin. You note that glycerine is in the soap but it’s not listed in the ingredients.

    • Hi Anne – Glycerin is a natural byproduct of the soapmaking reaction. Here’s how it gets there: soap is made from oils, coconut, olive, and palm oils in our case. An oil molecule is made up of three fatty acid chains attached to one glycerin molecule. During the soapmaking reaction, the fatty acids are blasted off of that glycerin backbone by a strong alkali, such as sodium or potassium hydroxide. The fatty acids combine with the sodium or potassium, forming a soap molecule. The hydroxide ion forms water, and the glycerin is left free floating. It’s not listed in our ingredients because we don’t add it. It’s part of the oils that are listed in the ingredients. Some soapmakers drain off this glycerin and sell it separately, but we prefer to leave it in there because it actually makes for a much softer afterfeel. It will not irritate or dry your skin.

    • Hi Karen – Yep! It’s a great option for dogs.

  5. Is there enough essential oil in your soaps… lavender, tea tree, orange, peppermint to “kill” germs or do I need to add more oils for this effect when using it for household uses?

    • Hi Tee – None of the essential oils in our soaps are strong enough alone to kill bacteria outright. However, the soap itself is your main warrior here. Soap gets rid of bacteria by attaching to it and water and getting it rinsed away. If you’d like an extra antibacterial punch, add 1/2 tsp. of pure essential tea tree oil. Killing germs is not so much the need as getting rid of them. This is because attempting to kill all germs is backfiring tremendously as shown by the well-documented rise of antibacterial resistant superbugs. Here’s one of many articles on this: Hope this helps!

  6. HI Lisa,

    I’m wondering if Dr. Bonner’s glycerin soap can be used to clean waxed or oiled canvas luggage without damaging the finish. The luggage in question is Filson.

    • Hi Joanne – I don’t have experience with this and I don’t want to lead you wrong. If the manufacturers instructions say something about using a “mild soap or detergent”, then our Castile or Sal Suds would be an excellent choice.

Leave a Reply

Your email address will not be published. Required fields are marked *